1. Field of the Invention
The invention relates to an implantable medical system, in particular a system for triggering the act of swallowing in swallowing disorders, so-called cervical dysphagia.
2. Description of the Related Art
Swallowing disorders occur, for example, when food is not correctly directed into the esophagus after the onset of the voluntarily initiated swallowing process because the sphincter muscle at the point of intersection between the trachea and the esophagus (the esophageal sphincter) is inactivated inadequately or not at all. This dysphagia may be caused by damage to certain areas of the brain, for example, or by the connecting nerves and is often a result of a stroke.
Dysphagias are among the physical impairments that have an especially negative effect on a patient's quality of life. In addition, cervical dysphagia is a concrete health threat, in particular due to the sequelae, such as malnutrition, dehydration, respiratory problems, dependency on tubal nutrition and/or tracheal cannulas, death and the high cost of the health care system.
Another risk is that unchewed food and overly large bites of food “remain stuck in the throat” and may even lead to an obstruction of the respiratory tract. This may come about due to the fact that the food slips into the trachea instead of entering the esophagus when the esophageal sphincter is activated inadequately or not at all. The result may be respiratory arrest and cardiac arrest.
This is also illustrated in particular by the fact that dysphagias are one of the most common causes of death of patients within the first year after a stroke.
Due to the increasing life expectancy and the associated neurological diseases (strokes) and oncological diseases (cancer) in the head and neck area, there has been a constant increase in the number of patients suffering from swallowing disorders (dysphagias).
In a stroke (incidence 24 of 100,000, prevalence 1,200 of 100,000 in western industrial nations) more than 50% of those affected suffer from clinically relevant swallowing disorders during the acute phase. Of this 50%, approximately half die or recover adequately, so that approximately 25% of stroke patients have chronic dysphagia.
A second group which is constantly increasing includes the area of the geriatric population. Dysphagias occur in 30-60% of elderly residents of nursing homes. Dysphagia almost always occurs with advanced dementia. Numerous other diseases and frequently neurological diseases are associated with dysphagias. For example, approximately 40-50% of patients with Parkinson's disease (prevalence 300-1,000/100,000) suffer from dysphagias, and approximately 30-40% of patients with multiple sclerosis (prevalence 100/100,000) suffer from dysphagias.
Exogenous systems known from the state of the art for treatment of cervical dysphagia include the VITALSTIM® system, which provides neuromuscular electric stimulation and stimulates the area of the anterior neck region from the outside during the swallowing process to trigger a contraction of the swallowing musculature.
This stimulation of the swallowing musculature is, however, aimed only at activation of individual or multiple muscles but not at initiation of the entire swallowing process. Results of studies of such systems have been disappointing so far.
Investigations of electric stimulation in the area of the throat, the palatopharyngeal arch and in the area of the neck with a different frequency and intensity have been and are being conducted and our studies with regard to the efficacy thereof, i.e., the positive influence on relevant swallowing parameters, have been tested but have not yet led to a system that enables a patient to have a virtually normal and natural swallowing action.